ASSESSMENT OF THE ANTIBACTERIAL ACTIVITY AND CYTOTOXIC EFFECTS OF CRUDE AND FRACTIONATED EXRACTS OF Jatropha carcus LEAF

Abstract

The increase in antimicrobial resistance by microbes globally is life threatening, it therefore become necessary to continuously search for alternative antimicrobial agents from natural sources such as plants. The aim of this study was to evaluate the antibacterial activity of the crude and fractionated extracts of Jatropha carcus leaf and to determine its cytotoxicity. Leaves of J. carcus were extracted with distilled water, methanol and petroleum ether. The extracts were subjected to phytochemical screening and antibacterial activity using agar well diffusion method against E. coli, P. aeruginosa, K. pneumoniae, Proteus mirabilis and S. typhi. Extracts that exhibited the highest antibacterial activity were further fractionated using n-hexane, ethyl acetate and n-butanol and their antibacterial activity evaluated. Cytotoxicity studies of the active crude and fractionated extracts were carried out using brine shrimp lethality assay. Phytochemical screening revealed the presence of some bioactive metabolites. The aqueous and methanol crude extracts were the most active against the test organisms with highest zone of inhibition of 15mm against P. aeriginosa. The highest minimum inhibitory concentration of aqueous extract was 25mg/ml against P. aeruginosa and the minimum bactericidal concentrations was 12.5mg/ml against K. pneumoniae and Proteus mirabilis. The highest MIC and MBC of methanol extract was against E. coli which was both recorded at 25mg/ml, and the ethyl acetate, n-butanol and n-hexane fractions showed 29mm, 22mm and 8mm zone of inhibition against K. pneumoniae, Proteus mirabilis and K. pneumoniae respectively. The result of cytotoxicity showed that Methanol n-butanol fraction was least toxic with L_C50 of 175.43µg/ml while methanol ethyl acetate fraction was the most toxic with 370.00µg/ml. The aqueous and methanol crude and fractionated extracts showed antibacterial and toxicity activity on the test organisms.